Regenerative hydrorefining of petroleum crude oil and catalyst therefor



United States Patent 3,249,556 REGENERATIVE HYDROREFINING OF PETRO- LEUM CRUDE OIL AND CATALYST THEREFOR John G. Gatsis, Des Plaines, Ill., assignor to Universal Oil Products Company, Des Plaines, L, a corporation of Delaware No Drawing. Filed Aug. 19, 1963, Ser. No. 303,178 11 Claims. (Cl. 252-415) The present invention relates to a regenerative process for the hydrorefining of petroleum crude oil, heavy vacuum gas oil, crude tower bottoms, vacuum tower bottoms, heavy cycle stocks, and other high-boiling hydrocarbon mixtures. More specifically, the present invention is directed toward the catalytic hydrorefining of excessively contaminated heavy hydrocarbonaceous material through the utilization of a process involving regeneration and recirculation of the catalyst employed therein.

In one embodiment, the present invention involves a I process for the hydrorefining of heavy hydrocarbon charge stocks for the purpose of effecting the destructive removal of nitrogenous and sulfurous compounds, and affords unexpected advantages in the removal of metallic contaminants and particularly for the conversion of the pentaneinsoluble portion of the hydrocarbon charge stock into useful pentane-s'oluble hydrocarbon products. Crude petroleum oil, and heavier hydrocarbon-fractions and/or distillates, such as crude tower bottoms, vacuum gas oil, etc., generally contain nitrogenous and sulfurous compounds in large quantities. In addition, crude oil and such heavier hydrocarbon fractions contain quantities of metallic contaminants which exhibit the tendency to exert detrimental effects upon the catalyst utilized in various processes to which the crude oil or portion thereof, or heavy hydrocarbon fraction, is ultimately subjected. The more common of such metallic contaminants are nickel and vanadium, although other metals including iron, arsenic, copper, etc., may be present. These metals occur in a variety of forms: they may exist as metal oxides or as sulfides, introduced into the crude oil as metallic scale or particles; they may be in the form of soluble salts of such metals; usually, however, they exist as organometallic compounds such as metal porphyrins and the various derivatives thereof.

Although the metallic contaminants existing as oxide or sulfide scale may be removed, at least in part, by a relatively simple filtering technique, and the water-soluble salts are at least in part removable by washing and subsequent dehydration, a much more severe treatment is generally required to remove the organo-metallic compounds, and to the degree required such that the resulting crude oil or heavy hydrocarbon fraction is suitable for further processing. Notwithstanding that the total concentration of these contaminants, such as metal porphyrins, is relatively small, for example, less than about p.p.m., calculated as the elemental metal, subsequent processing techniques will be adversely affected thereby. For example, when a hydrocarbon charge stock containing metals in excess of about 3.0 p.p.m., is subjected to a cracking process for the purpose of producing lowerboiling components, the metals become deposited upon the catalyst employed, steadily increasing in quantity until such time as the composition of the catalytic composite is changed to the extent that undesirable results are obtained.

In addition to the above-described contaminating influences, crude oils and other heavier hydrocarbon fractions generally contain high percentages of pentaneinsoluble material. For example, a Wyoming sour crude having a gravity, API 60 F., of 23.2, is contaminated by 2.8% by weight of sulfur, 2700 p.p.m. of total nitrogen, 100 p.p.m. of metal porphyrins (as elemental nickel Patented May 3, 1966 of pentane-insoluble asphaltenes. A more difficult charge stock to convert into a valuable hydrocarbon fraction, is a crude-tower bottoms product having a gravity, API 60 F., of 14.3, and contaminated by the presence of 3.08% by weight of sulfur, 3830 p.p.m., of total nitrogen, p.p.m. of metals and 10.93% by weight of asphaltenes. Asphaltenes are coke-precursors having the tendency to become immediately deposited within the reaction zone, and other process equipment, and onto the catalytic composite in the form of a gummy, high molecular weight residue. Since this constitutes a large loss of charge stock, it is economically desirable to convert such asphaltenes into useful hydrocarbon oil fractions.

The object of the present invention is to provide a more efficient process for hydrorefining such petroleum crude oils, than the processes currently being employed. A fixed-bed catalytic process, for hydrorefining these highly contaminated heavy charge stocks, is virtually precluded due to the difiiculty in maintaining the catalyst in an active condition. Various moving-bed processes, employing catalytically active metals deposited upon silica and/ or alumina, are extremely erosive, causing plant maintenance to become diflicult and expensive. The present invention teaches the preparation of a colloidally dispersed, unsupported catalyst useful in a regenerative slurry process, which catalyst will not causeextensive erosion of the process equipment. liquid hydrocarbon product which is more suitable for further processing, without experiencing the difliculties otherwise resulting from the presence of the above-described contaminants. The catalyst of the present invention is particularly advantageous in effecting the removal of the organo-metallic compounds without significant product yield loss, while simultaneously converting pentane-insoluble material into pentane-soluble liquid hydrocarbons, notwithstanding the high concentrations of the other contaminating influences.

In a broad embodiment, the present invention relates to a regenerative process for hydrorefining a hydrocarbon charge stock which comprises the steps of: (a) admixing said charge stock with at least one organo-metallic compound of the metals of Group VI-B having an atomic number greater than 24, Group V-B and the Iron-group; (b) decomposing said organo-metallic compound in said charge stock and reacting the resulting colloidal suspension with hydrogen; (c) separating the resulting reaction mixture to provide a hydrorefined liquid product and a catalyst-containing sludge; (d) hydrogenating said catalyst-containing sludge in the presence of an iodinecontaining compound and hydrogen; (e) combining at least a portion of said hydrogenated sludge with said hydrocarbon charge and reacting the resulting colloidal suspension with hydrogen as aforesaid.

In another embodiment, the present invention involves a process for hydrorefining a hydrocarbon charge stock which comprises the steps of: (a) admixing said charge stock with at least one carbonyl of the metals of Group VI-B, having an atomic number greater than 24, Group V-B and the Iron-group; b) heating the resulting mixture at a temperature less than about 310 C. and for a time suflicient to decompose said carbonyl; (c) reacting the resulting colloidal suspension with hydrogen at a temperature within the range of from about 225 C. to about 500 C. and under a pressure of from about 500 to about 5000 pounds per square inch gauge; (d) separating the resulting reaction mixture to provide a hydrorefined liquid product and a catalyst-containing sludge; (e) hydrogenating said catalyst-containing sludge in the presence of an iodine compound and hydrogen, at a temperature of from about 300 C. to about 450 C. and under an imposed The present process yields a the steps of: (a) admixing said crude oil with at least one organo-metallic compound of the metals of Group VI-B having an atomic number greater than 24, Group V-B and the Iron-group; (b) heating the resulting mixture at a temperature less than about 310 C. and for a time sufficient to decompose said organo-metallic compound; reacting the resulting colloidal suspension with hydrogen at a temperature above about 225 C. and at a pressure greater than about 500 pounds per square inch gauge; (d) separating-the resulting reaction mixture to provide a hydrorefined liquid product and a catalyst-containing sludge; (e) hydrogenating said catalyst-containingsludge in the presence of an iodine-containing compound and hydrogen, at a temperature of from about 300 C. to about 450 C. and under an imposed pressure Within the range of from 1500'to about 5000 pounds per square inch; (f) combining at least a portion of said catalyst sludge with said petro' leum crude oil and reacting the resultant colloidal sus' pension with hydrogen as aforesaid.

A limited embodiment of the present invention encompasses a process for hydrorefining a hydrocarbon charge stock which comprises the steps of: (a) admixing said charge stock with at least one organo-metallic compound of the metals of Group VI-B having an atomic number greater than 24, Group V-B and the Iron-group; (b) decomposing said organo-metallic compound in said charge stock, reacting the resultant colloidal suspension with hydrogen at a temperature in excess of about 225 C. and at a pressure greater than 500 pounds per square inch gauge; (c) separating the resulting reaction mixture to provide a hydrorefined liquid product and a catalyst containing sludge; '(d) hydrogenating said catalyst-containing sludge in the presence of iodine and hydrogen;

(e) adding from about 0.1% to about 1.0% of said organo-metallic compound, calculated as the elemental metal, to said hydrocarbon charge and combining at least a portion of said catalyst-containing sludge therewith; (f) decomposing said added organo-metallic compound as aforesaid and reacting, the resulting colloidal suspension with hydrogen as aforesaid.

From the foregoing embodiments, it is readily ascertained that the method of the present invention involves the preparation of a catalyst utilizing metals which are selected from Group VL-B, Group V-B and the Irongroup of the Periodic Table. The catalyst, prepared in accordance with the method of the present invention, may comprise one or more metals from the group of vanadium, niobium, tantalum, molybdenum, tungsten, iron, cobalt, nickel and mixtures of two or more. It is noted that the metal selected from Group VI-B, namely molybdenum and/ or tungsten, has an atomic number greater than 24. As stated in my Patent 3,173,860, March 16, 1965', organic chromium complexes, upon decomposition, do not yield comparable results upon'subsequent reaction with hydrogen, particularly with respect to the conversion of the pentane-insoluble material, and the destructive removal of the organo-metals such as nickel and/or vanadium porphyrins. The catalyst is prepared by initially dissolving an organic complex of the selected metal, or metals, preferably a carbonyl thereof, in the hydrocarbon charge stock containing the pentane-insoluble fraction which is to be converted into soluble hydrocarbons. The quantity of the organo-metallic compound employed is such that the colloidal suspension, or dispersion, which results when the organo-metallic compound is decomposed within the hydrocarbon charge stock, comprises from about 1.0% to about 10.0% by weight, calculated asthe elemental metal. Suitable organo-metallic compounds include molybdenum hexacarbonyl, tungsten hexacarbonyl, iron pentacarbonyl, molybdenum hexacarbonyl in combination with nickel formate, tungsten hexacarbonyl in combination with iron carbonyl, vanadium carbonyl, various cobalt carbonyls, etc. Heteropoly acids including phosphomolybdic, phosphotungstic, silicomolybdic, silicotungstic, etc. can be employed as the source of the metallic component.

The process is effected, as hereinabove set forth, by

initially dissolving the desired quantity of the organometallic compound, such as molybdenum hexacarbonyl, in the hydrocarbon charge stock. The resulting mixture is then heated, preferably in the absence of free hydrogen, at a temperature less than about 310 C. and for a time sufiicient to effect the decomposition of the hexacarbonyl, thereby resulting in a colloidal suspensions, or dispersion, of the metallic component with the hydrocarbon charge stock. The presence of free hydrogen during the decomposition of the organo-metallic compound has the tendency to affect detrimentally the activity of the catalyst with respect to the conversion of the pentane-insoluble fraction as well as the removal of nitrogen and sulfur. The colloidal dispersion is then passed into a suitable reaction zone maintained at a temperature within the range of from about 225 C. to about 500 C., and under a hydrogen pressure within the range of about 500 to about 5000 pounds per square inch gauge. In order to maintain the catalyst-in its decomposed form, either as the elemental metal, or as a lower oxide thereof, it is necessary that the reaction zone be maintained substantially completely free from carbon monoxide. Following the decomposition of the molybdenum hexacarbonyl, some carbon monoxide will be present in the gaseous phase; this is readily removed upon venting prior to passing the mixture into the reaction zone. Where some of the carbon monoxide is dissolved in the liquid phase, it is preferred to remove the same by suitable stripping means. When effected in a continuous manner, the process may be conducted in either upward flow or downward flow. The normally liquid hydrocarbons are separated from the total reaction Zone efliuent by any suitable means, for example, through the use of a centrifuge, orsettling tanks, the catalyst-containing sludge, after hydrogenation as hereinafter set forth, being recycled to combine with additional fresh hydrocarbon charge stock. The ammonia and hydrogen sulfide, resulting from the destructive conversion of sulfurous and nitrogenous compounds, are removed, along with any light paraflinic hydrocarbons including methane, ethane and propane, in a gaseous phase. Prior to combining the catalyst-containing sludge with additional fresh hydrocarbon charge, the latter is admixed with additional molybdenum hexacarbonyl in an amount of from about 0.1% to about 1.0%, calculated as elemental molybdenum. Consequent- 1y, from about 0.1% to about 1.0% by weight of molybdenum,:or other catalytic metal is withdrawn from the catalyst-containing sludge prior to combining the latter with the fresh hydrocarbon charge stock. In this manner,

the desired concentration of the catalytically active metal is readily maintained within the range of from about 1.0% to about 10.0% by weight of the hydrocarbon charge stock. The metal contained Within the sludge withdrawn from the process, existing as the element or in a combined form, may be converted back to the organo-metallic compound by any of the well-known chemical means found in the prior art relating thereto.

Prior to combining the catalyst-containing sludge with the fresh hydrocarbon charge stock, the same is subjected to hydrogenation with an iodine-containing compound. In this manner, the metallic component within the sludge is reactivated, or regenerated, and the heavy hydrocarbonaceous sludge is rendered more susceptible to conversion when recycled to combine with fresh charge stock. The iodine-containing compound is employed in an amount within the range of about 0.05% to about 5.0% by weight,

calculated as elemental iodine, and based upon the weight of the catalyst-containing sludge. 'Iodoform, hydrogen iodide and iodine (are particularly preferred as the hydrogenating component, although metallic iodides from the metals of Group II of the Periodic Table can be employed with an acceptable degree of success, and includ zinc iodide, cadmium iodide, beryllium iodide, magnesium iodide, calcium iodide, mixtures of two or more, etc. These metallic iodides can also be utilized in combination with the foregoing iodine compounds; for example, the catalyst-containing sludge can be hydrogenated in the presence of iodoform and zinc iodide employed in an amount within the aforesaid range.

Although the process of the present invention is conducted in the presence of hydrogen, the decomposition of the organo-metallic compound, such as molybdenum hexacarbonyl, is necessarily effected in the absence thereof. The removal of carbon-monoxide during the decomposition is also important because it will facilitate the decomposition of molybdenum hexacarbonyl. Depending upon the particular organo-metallic compound which is selected as the catalyst source, the dispersed material will be the elemental metal or a lower oxide form thereof. In any event, it is understood that the stated concentrations are computed on the basis of the elemental metal. The decomposition of the organo-metallic compound is conducted at a temperature less than about 310 C. in order to avoid initial cracking of the petroleum crude oil or heavy hydrocarbon fraction, prior to effecting complete decomposition. The quantity of hydrogen, present in the reaction zone in admixture with the colloidal suspension, is determined by the pressure imposed upon the reaction zone; as above set forth, this pressure will be within the range of about 500 to about 5000 pounds per square inch gauge.

The following examples are given to illustrate the process of the present invention, the effectiveness thereof in removing nickel and vanadium porphyrins from a petroleum crude oil, and in converting p'entane-insolub'le asphaltenes while simultaneously effecting the conversion of sulfurous and nitrogenous compounds into sulfur and ni-.

trogen-free hydrocarbons. It is not intended that the present invention be unduly limited to the catalyst, charge stock, and/or operating conditions employed in this illustration. The concentration of the nickel and vanadium metals, remaining in the reaction zone liquid product effluent, following separation from the catalyst-containing sludge, is determined through the utilization of spectrographic emission.

Example I The crude oil employed to illustrate the benefits afforded through the utilization of the present invention was a Wyoming sour crude oil having a gravity of 232 API 60 F and containing 2.8% by weight of sulfur, approximately 2700 ppm. of nitrogen, 18 p.p.m. of nickel and about 81 p.p.m. of vanadium, as metal porphyrins, computed on the basis of the elemental metal. In addition, the sour crude consisted of 8.39% by weight of pentaneinsoluble asphaltenes. As hereinafter indicated, the process of the present invention effects the conversion of a significant proportion of such asphaltenes, and to the degree that the same no longer exert a deterimental effect upon further processing.

The colloidally dispersed catalysts were prepared by decomposing the indicated org-ano-metallic compounds within the Wyoming sour crude oil, thereafter subjecting the mixture to conversion in a rotating autoclave maintained at about 400C., and under an imposed hydrogen pressure of about 200 atmospheres. Each of the colloidal suspensions remained in the autoclave at the foregoing conditions for a period of from about 4 to about 8 hours or more. Molybdenum hexacarbonyl, in an amount of 23.3 grams, was admixed with 200 grams of the Wyoming sour crude, the mixture being charged to the rotating autoclave and heated to a temperature of 250C. for a period of 3 hours. After venting to remove carbon monoxide, the autoclave was pressured to atmospheres with hydrogen, and then heated to a temperature of 400 C. for a period of about 3 hours, the final pressure being about 2.00

' atmospheres. The gravity, API 60 F., of the resulting normally liquid product efiiuent, following separation from the catalyst-containing sludge, was 40.1, indicating a very significant degree of conversion to lower-boiling hydrocarbon products. Upon analysis, the liquid product indicated only 7.1 p.p.m. of nitrogen, about 0.02% by weight of sulfur, about 0.10% by weight of pentane-insoluble asphaltenes, less than about 0.02 ppm. of nickel and less than about 0.02 p.p.m. of vanadium. When utilizing 23.3 grams of molybdenum hexacarbonyl decomposed in situ, in the presence of hydro-gen, the final liquid product was found to contain 347 p.p.m. of nitrogen compared to 7.1 p.p.m. of nitrogen as hereinabove set forth.

A mixture of 23.3 grams of molybdenum hexacarbonyl and 2.5 grams of nickel formate were added to 200 grams of the Wyoming sour crude, initially heated to a temperature of 250 C. for a period of 4 hours, to decompose the nickel formate and molybdenum hexacarbonyl. The mixture was placed in the rotating autoclave under a presure of 100 atmospheres of hydrogen; upon being heated to a temperature of 400 C., the pressure increased to a level of about 200 atmospheres. These conditions were maintained for a period of 8 hours, and the resulting normally liquid product effluent indicated 124 p.p.m. of nitrogen, 0.02% by weight of sulfur, less than 0.1% by weight of pentane-insoluble asphaltenes, less than 0.04 p.p.m. of nickel and less than 0.04 p.p.m. of vanadium.

Example II Molybdenum hexacarbonyl, in an amount of 23.3 grams, is admixed with 200 grams of the Wyoming sour crude, the mixture being charged to the rotating autoclave and heated to a temperature of 250C. for a period of 3 hours. After venting to remove carbon monoxide, the mixture is passed into a suitable reaction zone maintained under a hydrogen pressure of about 200 atmospheres, and at a temperature of about 400C. The total reaction zone product eflluent is passed into a centrifugal separator from which the normally liquid hydrocarbon product, substantially free from solids, is removed. This liquid product indicates less than about 10 p.p.m. of nitrogen, less than 0.02% by weight of sulfur, about 0.20% by weight of pentane-insoluble asphaltenes, less than about 0.02 p.p.m. of nickel and less than about 0.02 p.p.m. of vanadium.

The catalyst-containing sludge, in an amount of about 27.0 grams, is admixed with an amount of iodoform sufficient to supply about 3.5% by weight of iodine within the resulting mixture. The mixture is placed Within the rotating autoclave and brought to a temperature of about 350C. after being pressured with hydrogen, the final pressure being about 2000 pounds per square inch. After 4 hours at the stated conditions, the contents of the autoclave are allowed to cool to about room temperature.

The catalyst-containing sludge, removed from the autoclave, is combined with fresh hydrocarbon charge after about 0.1% to about 1.0% of the solid catalyst particles, calculated as the elemental metal, are removed therefrom. An additional amount of molybdenum hexacarbonyl, from about 0.1% to about 1.0% by weight, calculated as molybdenum, is then added to the mixture of fresh hydrocarbon charge and catalyst-containing sludge. then heated to a temperature of about 250C. and for a time suflicient to decompose the added molybdenum hexacarbonyl. The resulting colloidal suspension is then passed into the reaction zone as hereinbefore descirbed. passed into the reaction zone as hereinbefore described.

Analyses of the resulting normally liquid product effluent indicate a nitrogen concentration less than 10 p.p.m., about 0.02% by Weight of sulfur, about 0.30% by weight of pentane-insolubles and about 0.10 p.p.m. of total metals.

The mixture is The foregoing specification and examples clearly illus trate the advantages aiforded the hydrorefining of'petroleum crude oils through the utilization of the process of the present invention. It is of particular interest to note that the concentration of nickel and vanadium, existing as organo-metallic compounds, as well as the pentaneinsoluble asphaltenes, are decreased to a level permitting subsequent utilization of the crude oil either for further processing or distillation, and more unexpectedly, that at least a portion of the crude oil Was converted into lowerboiling hydrocarbon products.

I claim as my invention:

1.:A method of regenerating a hydrorefining catalyst dispersed in a hydrocarbon, said catalyst being a Group VI-B metal having an atomic number greater than 24, a Group V-B metal or an Iron-group metal, which method comprises hydrogenating said dispersion incontact with an iodine compound and hydrogen.

2. The method of claim l-further characterized in that said iodine compound is an iodide of a metal of Group II of the Periodic Table.

3. The method of claim 1 further characterized in that said iodine compound is iodoform.

4. The method of claim 1 further characterized in that said iodine compound is hydrogen iodide.

5. The method of claim 1 further characterized in that I said metal is molybdenum.

6. The method of claim 1 further characterized in that said metal is vanadium.

7. The method of claim 1 further characterized in that said metal is tungsten.

8. A method of regenerating a hydrorefining catalyst dispersed in a hydrocarbon, said catalyst being a Group VI-.B metal having an atomic number greater than 24, a Group V-B metal or an Iron-group metal, which method comprises hydrogenating said dispersion in contact with an iodine compound and hydrogen, the hydrogenation being efiected at a temperature of from about 300 C. to about 450 C. and under an imposed pressure Within the range of from 1500 to about 5000 pounds per square inch.

9. The method of claim 8 further characterized in that said iodine compound is an iodide of a metal of Group II of the Periodic Table.

10. The method of claim 8 further characterized in that said iodine compound is iodoform.

11. The method of claim 8 further characterized'in that said iodine compound is hydrogen iodide.

References Cited by the Examiner D UNITED STATES PATENTS 3,165,463 1/1965 Gleim et al. 208264 3,166,494 1/1965 Gatis et al 208264 3,169,919 2/ 1965 Gatis et al 208264 DELBERT E. GANTZ, Primary Examiner;

S. P. JONES, Assistant Examiner. 

1. A METHOD OF REGENERATING A HYDROREFINING CATALYST DISPERSED IN A HYDROCARBON, SAID CATALYST BEING A GROUP VI-B METAL HAVING AN ATOMIC NUMBER GREATER THAN 24, A GROUP V-B METAL OR AN IRON-GROUP METAL, WHICH METHOD COMPRISES HYDROGENATING SAID DISPERSION IN CONTACT WITH AN IODINE COMPOUND AND HYDROGEN. 